This invention relates to an electrical noise absorber and, in particular, to an electrical noise absorber provided with a magnetic body attached to a flat cable of an electronic device for absorbing electrical noise which is generated within the device or which enters from the outside into the device through the flat cable, and a magnetic body fixing device for supporting the flat cable in the magnetic body.
The applicant of this invention proposed such electrical noise absorber in U.S. Design Patent No. 318,045, in which the ferrite core as a magnetic body held in a pair of ferrite core holders is attached around a wire ribbon to absorb electrical noise flowing through the wire ribbon. As shown in FIG. 11, a ferrite core 533 is attached around a wire ribbon 531 composed of multiple signal wires, and absorbs electrical noise flowing through the wire ribbon 531. The ferrite core 533 is composed of an upper piece disposed over a lower piece in the direction shown by an arrow B in FIG. 11. In the middle of the ferrite core 533, a slot 535 is formed by recesses in the upper and lower pieces for passing through the wire ribbon 531. Both side edges of the ferrite core 533 are held by ferrite core holders 537 having ferrite core presses or securing members 539 for pressing the upper and lower pieces of the ferrite core 533 toward one another. A sufficient magnetic flux density is thus developed in the ferrite core 533 for effectively absorbing the electrical noise flowing through the wire ribbon 531. The ferrite core holders 537 have guide slots 541 for receiving the side edges of the wire ribbon 531 when the ferrite core holders 537 are attached to the ferrite core 533 around the wire ribbon 531.
As shown in FIG. 12, however, when the width La of the wire ribbon 531 is smaller than the inner dimension Lb of the ferrite core 533, the ferrite core 533 is displaceable relative to the wire ribbon 531. If the surface of the wire ribbon 531 peels off or is worn because of the slippage of the ferrite core 533 around the wire ribbon 531, the signal wires of the wire ribbon 531 are exposed to the environment, thus causing a short circuit.